This invention relates generally to power plants having gas driven turbine engines and more specifically to a power plant incorporating both a gas driven turbine and a magnetohydrodynamic (MHD) generating system.
Magnetohydrodynamic (MHD) power generating systems have found substantial prior use in supplementing other power plant operation, particularly jet engines or the like whose operation is characterized by the generation of hot gases suitable to achieve MHD interactions, and by reason of the fact that MHD power generation does not require the use of moving parts which are adversely affected by exposure to the high temperature of the gases.
In the incorporation of a combustion MHD generator into a power plant, it would be desirable to locate the generator near and upstream of a gas turbo-electric generator in order to make optimum use of the combustion gases to provide for electrical power generation. However, a turbine incorporated into the engine plant and configured to be driven by the flow of the combustion gases must, for feasible operation, be supplied with a lower temperature gaseous flow than that which is characteristic of the exhaust of the MHD generator. The present invention solves this problem by providing means, between an MHD generator and a gas turbine, to cool and supplement the MHD exhaust to provide suitable gas temperature, pressure and velocity to efficiently drive the turbine, and at the same time to obtain greater overall energy conversion efficiency for the two systems (MHD and gas turbine) than that for each system used separately.
According to the present invention, a set of cooling and mixing fins are introduced as a coupling means between an MHD generator and the turbine section of a power plant incorporating a gas turbine engine. The cooling fins are disposed in the diffuser section of the engine duct between the MHD generator and the turbine, and are configured to supply cool compressed gas, vapor, or liquid for mixing with the combustion gases exiting that region of the duct adjacent the MHD generator. The effect of the fins is to lower the temperature of gases entering the turbine so that the turbine blades and other affected engine parts may operate at a temperature lower than the temperature of the MHD exit gas, and to raise the pressure of gases entering the turbine to a level at which the turbine will operate a reasonable efficiency. The overall result of the introduction of the cooling/mixing fins of the present invention is that by combining, for example, an MHD generator of about 20% thermal efficiency with a gas turbine generator of about 40% turbo-electric efficiency, the overall energy conversion efficiency of the system may be about 50%. Some energy is lost in the coupling process, since coolant is pumped through the fins. However, by combining the MHD generator and turbine in a system coupled according to the invention described herein, no additional machine volume per unit energy produced is required, the weight per energy unit produced by the coupled system is therefore reduced, and fuel efficiency of the power plant is significantly improved.
It is, therefore, an object of the present invention to provide an improved gas turbine power plant.
It is another object of the present invention to provide high efficiency coupling means between the turbine of a gas turbine power plant and an MHD generator incorporated therein.
It is a further object of the present invention to provide a high efficiency, relatively low temperature operation, gas turbine.
These and other objects of the present invention will become apparent as the detailed description of certain representative embodiments thereof proceeds.